Use of wireless communications techniques for electronic devices is becoming increasingly popular. Wireless devices provide convenience and ease of use. Bluetooth has become particularly prevalent as a wireless communications protocol. It provides versatile mechanisms for transmitting digital signals over short distances with very low power consumption. Bluetooth has become a ubiquitous standard amongst mobile phones, tablet computers, personal computers, wireless headphones, automobiles, and a wide variety of other device types. As a result, Bluetooth devices are readily interoperable with other electronic devices. Meanwhile, high production volumes result in ready availability and relatively low cost for transceiver chipsets and circuit boards, further reinforcing the widespread adoption of the standard.
Bluetooth Low Energy (“BLE”) is a subprotocol defined within the Bluetooth 4.0 protocol, that enables highly energy-efficient transfer of data between a client device (e.g. a sensor) and a server device (e.g. a mobile phone or personal computer). BLE can be particularly valuable for battery-operated devices, for which minimizing power consumption may be critical.
While the prevalence of Bluetooth and power-efficiency of BLE provide many advantages, some device types, particularly in the context of medical instrumentation, give rise to communication requirements that may not be well-satisfied by standard Bluetooth implementations. For example, many types of instrumentation may require transmission of multiple signal types, which would traditionally be conveyed by multiple wires or multiple wireless radios. However, consumer electronic devices may be limited in the number of radios provided, while sensors with multiple radios may require greater power consumption, resulting in larger batteries and/or worse battery life. Meanwhile, BLE bandwidth limitations may impact sensor performance. For example, while humans can typically perceive sounds ranging from about 20 Hz to about 20 kHz, BLE as a protocol does not have enough bandwidth to transmit the entirety of the human audio spectrum, due to small packet size and slow packet speed. Traditional Bluetooth and BLE implementations may be particularly disadvantageous or limiting for medical devices such as wireless cardiac devices.